DTC C1B6F Accumulator Pressure Too Low: Notes

1. - 

DTC detecting condition: 

Accumulator pressure drops significantly and the condition continues (diagnosis codes are stored and buzzer is triggered once conditions are met).

Trouble symptom: 

• Brake cannot be controlled.
• Regenerative brake cannot be controlled.
• Brake assist does not operate.
• EyeSight functions (ACC/PCS) do not operate.

Wiring diagram: 

Electronic controlled brake system Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>ELECTRIC CONTROL BRAKE SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Using the Subaru Select Monitor, perform the clear memory of [Electric Brake Booster]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
   2. Read the DTC of [Electric Brake Booster] using the Subaru Select Monitor. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is only DTC C1B6F displayed?

   Yes:  Go to  2.

   No:  Perform the diagnosis according to the DTC. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

2. CHECK CONNECTOR  .

   Check the connecting condition of the brake accumulator assembly connector.

   Is there looseness, deformation, or corrosion at the connectors?

   Yes:  Repair or replace the connector.

   No:  Go to  3.

3. CHECK BRAKE ACCUMULATOR ASSEMBLY  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the brake accumulator assembly connector.
   3. Measure the resistance between terminals of brake accumulator assembly.

      Terminals 

      No. 1 - No. 3: (Resistance: 10 Ω or less)

      No. 2 - No. 4: (Resistance: 10 Ω or less)

      No. 1 - No. 2: (Resistance: Less than 1 Ω)

      No. 3 - No. 4: (Resistance: Less than 1 Ω)

   Does the resistance indicate the standard value?

   Yes:  Go to  4.

   No:  Replace the brake accumulator assembly. Ref. to BRAKE>BRAKE ACCUMULATOR ASSY .

4. CHECK DATA MONITOR  .
   1. Connect the brake accumulator assembly connector.
   2. Disconnect the brake stroke sensor connector.
   3. Using Subaru Select Monitor, display [Accumulator Pressure] in [Data Monitor] of [Electric Brake Booster]. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DATA MONITOR .
   4. Depress the brake pedal several times so that the pump motor operates, then wait until it stops.
   5. Wait for 30 seconds from the moment the pump motor stops, then check the amount of [Accumulator Pressure] drop and the condition of the pump motor.

   Is the amount of [Accumulator Pressure] drop after 30 seconds less than 2.50 MPa, and does the pump motor start operating within 30 seconds?

   Yes:  Go to  5.

   No:  Currently, it is normal. There may have been a temporary poor contact in the harness and connector or a temporary noise interference.

5. CHECK DATA MONITOR  .
   1. Turn the ignition switch to OFF.
   2. Connect the brake stroke sensor connector.
   3. Using Subaru Select Monitor, display [Servo Pressure] in [Data Monitor] of [Electric Brake Booster]. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DATA MONITOR .
   4. Depress the brake pedal to the floor and check to see if the [Servo Pressure] changes in response to amount of brake pedal stroke.
      NOTE: [Servo Pressure] should not rise when the pedal is released.

   Does the [Servo Pressure] remain risen?

   Yes:  Replace the brake booster assembly (with the master cylinder). Ref. to BRAKE>BRAKE BOOSTER .

   No:  Replace the brake accumulator assembly. Ref. to BRAKE>BRAKE ACCUMULATOR ASSY .